The band, which was forced to cancel its Houston show days earlier due to the storm, wrote the song as the region was enduring historic flooding.

After acknowledging that he and the band all "grew up loving country music, and, of course, that's kind of what we think of when we go to Texas," Martin asked the crowd to bear with them.

"This is a new song, and we'll never play it again," Martin said. "It's a once-off. It's called 'Houston.' We're going to sing it in Miami for everybody here and then we're going to send it over there to everyone who missed the show."

Vowing to return to Houston, Martin and band huddled and tentatively started a twangy little number.

"I'm dreaming of when I get back to Houston," sang Martin, replete with a touch of Johnny Cash-ian twang. Describing it as "that city where they send you into space," Martin crooned of "Corpus Christi, Harris County, Galveston," of "a harmony that hums down there in Houston," and urged the region to "keep on keeping on."

Merle Haggard it wasn't (and everyone's a critic), but the performance drew huge applause from fans and went viral on Tuesday morning.

Coldplay's quick-turnaround ditty is hardly the first to document such deluges. Johnny Cash's "Three Feet High and Rising" occurred in real time as a family struggled to keep dry.

In Charley Patton's "High Water Everywhere," the country blues singer recalled the lives lost in the Great Flood of 1927, which consumed the Mississippi Delta and spawned dozens of songs: "Oh, Lordy, women is groaning down / Oh, Lordy, women and children sinking down," Patton sang. "I couldn't see nobody home, and was no one to be found."